1. Field of the Invention
The present invention relates to dust suppression. In another aspect, the present invention relates to a dust suppression suspension, to a dust suppression emulsion, and to a method of suppressing fugitive dust emission. In yet another aspect, the present invention relates to a dust suppression suspension of sugar particles suspended in an oil base, and further including an emulsifier, thickener, surfactant and pour-point depressant, to an emulsion made from such a slurry, and to a method of dust suppression using such slurry and emulsion.
2. Description of the Related Art
Suppression of dust is a common problem that has been of concern to industry for many years and is encountered in a whole host of industrial and other activities.
For example, dust may be generated in mines and ordinary roadways, in playgrounds, training camps, dirt walks and the like.
As another example, dust generation is common in coal mining, cement production and metal ore refining. Dust generation is also common in the transportation of dust generating materials in, for example, truck beds, railroad cars, and trailers. This is especially true of material transported by trains, which travel about 40 or so miles per hour, and even more true when such trains traverse a tunnel, thereby creating turbulence and dust.
In the production of Portland cement, the raw materials utilized include limestone, clay, shale, iron containing materials and siliceous materials. These materials are normally obtained by drilling and blasting techniques with the raw materials then being transported from the quarry to crusher and screening operations.
The crushed and/or screened materials are then further processed to obtain "Portland cement clinker" which consists essentially of hydraulic calcium silicates. Portland cement is generally formed by adding gypsum and then pulverizing the mixture by means of a ball mill or the like. It is then either packaged or stored. The end user adds water, aggregate, sand, etc. to the dry ground clinker-gypsum mixture to form the desired mortar or concrete.
The problem of fugitive dust emission is generally present at the various points in the Portland cement process.
The prior art is replete with instances of attempts to overcome the prior art limitations suppress dust emission.
U.S. Pat. No. 2,195,573, issued Apr. 2, 1940 to Kritchevsky discloses a method of overcoming dust problems in mines and ordinary roadway. As disclosed by Kritchevsky, a prior art method of overcoming dust problems in mines included utilizing an incombustible dust such as stone dust to decrease the inflammability of the coal dust. While suitable to decrease the inflammability of the coal dust, the stone dust does not alleviate the dust problem and actually accentuates it. Other prior art methods included water spraying the dust in roadways and passages and the like, but the water generally has little, if any, affinity for the dust. Accordingly, with water spraying, the water forms in segregated pools on top of the dust with the result not only that the dust situation is not helped, but formation of puddles on the road hinders and makes travel difficult and unsatisfactory. In an effort to overcome the prior art limitations, Kritchevsky discloses the use of an aqueous solution of condensation products of alkylolamines and higher organic acids, especially the higher fatty acids.
U.S. Pat. No. 2,399,465, issued Apr. 30, 1946 to Butcher discloses an improved liquid spraying agent adapted to inhibit the surface dusting of the soil in playgrounds, training camps, dirt walks and the like. As disclosed by Butcher, prior art methods included use of aqueous solutions of calcium chloride and heavy petroleum oils of asphalt base. However, calcium chloride is readily washed away by rain, and the oils are undesirable because of their stickiness, odor, color and rather low wetting power. Butcher discloses a dust laying composition comprising a relatively non-volatile or high-boiling petroleum distillate, admixed with a small amount of oleic acid, either alone or in combination with a metal naphthenate.
U.S. Pat. No. 2,448,605 issued to Kleinicke discloses a novel composition adaptable for use in the treating of coal, coke and the like and more particularly for allaying and preventing dusting of coal, coke and the like. As disclosed by Kleinicke the prior art use of petroleum oil to allay dust was subject to substantial limitation in this it was not substantially effective in the treatment of damp and wet or washed coal due to the immiscibility of water and oil. In an effort to overcome the prior art limitations, Kleinicke disclosed a dust preventative composition comprising an unsaturated fatty acid having 18 carbon atoms, a petroleum oil soluble wetting agent, a low viscosity hydrocarbon distillate.
U.S. Pat. No. 4,380,459, issued Apr. 19, 1983 to Netting discloses a method for removing dust particles from the air by capture by a collapsible aqueous foam having a controlled instability such that less than all of the potential drainage liquid has drained in five minutes after foam generation. The foam generally includes water, a surfactant and a synthetic gum. The synthetic gum is disclosed as being selected from carboxymethyl cellulose, cationic cellulosic resin, hydroxy propyl cellulose, polyethylene oxide resin, polyethylene glycol resin and acrylic acid polymer. The surfactant is disclosed as being a mixture of salts of alkylated benzene sulfonic acids.
U.S. Pat. No. 4,425,252, issued Jan. 10, 1984 to Cargle et al. discloses a method for the abatement of respiratory coal dust by the spraying of an aqueous solution, comprising a water soluble salt of an alkyl aryl sulfonic acid and a nonionic surfactant having an HLB of from about 10 to about 16, on a coal seam face being mined so as to readily wet the coal dust adjacent thereto resulting in the rapid removal of the dust from the air.
U.S. Pat. No. 4,897,218, issued Jan. 30, 1990 to Roe discloses a method of suppressing dust generation emanating from cement clinker by applying a foamed water/surfactant solution thereto. The surfactant is generally selected from sodium dodecylbenzene sulfonates, sodium lauryl sulfates, sodium alpha olefin sulfonates and sodium salts of fatty acids. The surfactant is generally diluted with water at the job site, foamed and sprayed as a foam on the hot cement clinker.
U.S. Pat. No. 4,971,720, issued Nov. 20, 1990 and U.S. Pat. No. 5,143,645, issued Sep. 1, 1992, both to Roe disclose a method for suppressing process dust emissions by applying a foam formed from demineralized water and a foaming agent. The foaming agent is selected from among salts of fatty acids, alkyl sulfates, and alkyl aryl sulfonates.
Parent U.S. application Ser. No. 08/135,056 disclosed application of water and polysaccharide to dust emitting materials to suppress dust generation. One application method was the direct application of a water and polysaccharide solution, which suffered from a high viscosity and thus subsequent application difficulties, from bacterial attack on the solution, and from poor economics resulting from the transport of low solids solutions in water. An alternative application method of applying dry polysaccharide to the dust emitting material followed by application of water, suffered from the need for specialized equipment and other operational difficulties.
Thus, in spite of the above methods of suppressing dust emission, there still exists a need in the art for an improved method of suppressing dust.
Other needs in the art will become evident to those of skill in the art upon review of this patent specification.